1. Field of the Invention
The present invention relates to telephony, and in particular relates to systems and methods which are used to provide information to an intercept and/or directory assistance operator as to the status of a plurality of subscriber telephone numbers.
2. Description of the Prior Art
Printed telephone directories currently used by telephone companies in the United States and Canada are usually prepared on an annual basis. During any yearly period, a large number of subscribers in any telephone company's area receive new telephone numbers, as they move into that company's area. Since such changes cannot be found in the annual printed directory, telephone utilities are required to provide a service known as "directory assistance," in which the calling party can dial a code, usually a three-digit number, and is then connected with a directory assistance operator in a central office facility.
In such a system, the telephone company must then provide the directory assistance operator with an updated list of changes (additions and deletions) in the printed directory. Since many directory assistance calls require information regarding telephone numbers appearing in the printed directory, then the directory assistance operator must also have this information available. Further, in order to make this entire amount of information available to the directory assistance operator in a readily accessible form, the updated list must be integrated in some fashion with the printed directory information. This is usually done on an alphabetical basis, in the same manner as the annual printed directory.
Additionally, when a telephone subscriber's service is discontinued, most telephone companies are required to route any incoming calls for that disconnected number to an "intercept" operator, who advises the calling party that the number has been disconnected. If the subscriber has a new number, the intercept operator will then advise the calling party of that new number. In order to accomplish this, the intercept operator must also be provided with an updated list of discontinued numbers and the corresponding new number.
In order to provide the updated directory assistance and intercept operator lists referred to above, many telephone companies have daily lists printed which are then picked up and distributed by messenger service. In telephone systems of any size, the logistics of such an arrangement becomes quite burdensome.
Further, some telephone utilities have now been authorized by their respective public service commissions to charge for directory assistance calls where the called number is listed in the printed directory. The purpose of such a charge is to discourage the subscriber's reliance on the directory assistance operator in cases where the called number can be readily determined from the directory.
In some states, this authorization by the respective public service commission requires that the telephone company provide the directory assistance service free for each subscriber as to a limited number of directory assistance calls, the charge thereafter being only in effect after this threshold is reached. In such a situation, the telephone company may therefore determine three factors: first, the called number; second, whether the called number is actually printed in the most recent published directory; and finally, the calling number, so that an appropriate accounting as to the minimum number of free calls or charges beyond the number of free calls can be made. It has also been suggested that certain classes of subscribers, for example blind persons, be allowed to make an unlimited number of free directory assistance calls.
There are a variety of prior art patents that disclose telephone systems for intercepting calls and providing an input to the calling party with regard to the status of the called telephone number. In U.S. Pat. No. 2,899,503, Dubuar, discloses an automatically operated switching device for providing a machine announcement on intercepted calls.
Pharis, in U.S. Pat. No. 2,925,472, discloses an automatic arrangement similar to that taught by Dubuar.
In U.S. Pat. No. 2,968,700, Myers, discloses a telephone intercept system providing for intercept translation. Kezuka, in U.S. Pat. No. 3,586,780, discloses a system for automatically advising a calling party that the called telephone number has been changed and for advising him of the newly allotted number, if any.